Maternal infections during pregnancy have been linked to an increased risk of autism and other neurological disorders in the child. Dr. Palmer's laboratory has found that giving a mild infection to rats and mice during pregnancy causes changes in the production of brain cells in the developing offspring, a process which might also contribute to the development of autism in humans. Maternal infection is likely to affect fetal development via proteins that are produced as part of the mother's immune response. These proteins could affect fetal development in several ways, including by acting directly on the developing fetal brain or by impairing the ability of the mother's placenta to supply blood and oxygen to the fetus. In this study, Dr. Palmer and colleagues will evaluate these two hypotheses to determine how maternal immune proteins affect both the placenta and fetal brain development. If placental function is found to be impaired by the immune response, they will test several clinical strategies aimed at preserving placental function to determine whether these therapies allow the fetal brain to develop properly even in the presence of infection.